Most textures:
Minetest Game 5.0.0-dev

Lapis lazuli textures:
[lapis] by LNJ (WTFPL)
https://forum.minetest.net/viewtopic.php?f=11&t=11287

Nether textures:
[nether] by PilzAdam (CC BY-SA 3.0)
https://forum.minetest.net/viewtopic.php?t=5790

Terracotta:
[bakedclay] (WTFPL)

Quartz ore:
[quartz] by JackWilliam (CC BY-SA 3.0)
https://forum.minetest.net/viewtopic.php?t=16426

Quartz blocks:
[quartz] by Evergreen (MIT)
https://forum.minetest.net/viewtopic.php?t=5682

Most farming items, cococa beans:
[farming] by TenPlus1
https://forum.minetest.net/viewtopic.php?id=9019

Meat items, egg, rabbit hide, leather, feather:
[mobs], [mobs_animal] by TenPlus1 (MIT)
https://forum.minetest.net/viewtopic.php?f=11&t=9917

Craft guide icon:
[craftguide] by kilbith (MIT)
https://forum.minetest.net/viewtopic.php?t=14088

Coarse Dirt, Bedrock, Golden Apple, Normal sandstone side:
Wuzzy
